In the pantheon of medical innovations, the home pregnancy test is a relatively big one. It enabled a woman to take that emotional moment of finding out if she’s expecting out of the doctor’s office and plunk it squarely in the more private confines of her bathroom.

As the first home pregnancy test from e.p.t. celebrates 35 years of making baby news more accessible, historians are hoping to document its evolution from the first, mini chemistry set-tests that debuted in 1977 to the sleeker stick-based versions on shelves today. At the same time, they’e also highlighting the impact the tests have had in raising awareness about prenatal care and giving women more power to influence the healthy development of their babies.

More than a few women save their pregnancy tests — the tell-tale purplish line or plus sign are a keepsake of the instant they learned that life was about to change in ways they could only guess at. But the first tests took two hours to generate a result (compared to the two minutes it takes today), and the inaugural version comprised a contraption including a plexiglass box containing a few test tubes, a dropper, some solution and a mirror. It worked using only first-morning urine, which is the most concentrated, and had to be handled gingerly. But did anyone actually hang on to one of the original clunkers? Somehow, test tubes don’t have the same keepsake appeal as a discreet wand.

And yet, historians remain hopeful. So far, the Smithsonian is interested in acquiring an original test kit; so is the history office of the U.S. Food and Drug Administration and the Dittrick Museum of Medical History at Case Western Reserve University. “Everyone wants one,” says FDA historian John Swann. “It’s a collector’s item.”

The tests represent an important milestone in using an antibody to detect the hormone hCG, which is secreted during pregnancy, and putting that technology in the hands of not just health care professionals, but the women who would be directly affected by the results. Researchers don’t consider this some fanciful quest. The home pregnancy test may cost only $10 or so, but its significance is felt in pregnancy outcomes everywhere. Allowing women to learn they’re pregnant with 99% accuracy as soon as they’ve missed their period — if not sooner — enables them to start acting like they’re pregnant right away. If they’re not already taking prenatal vitamins, they can start; if they’re smoking or drinking, they can stop. “It really puts women in control of what’s happening to their bodies at a much earlier time,” says Sarah Leavitt, who wrote an in-depth history of the pregnancy test when she was a historian at the National Institutes of Health (NIH).

The research that serendipitously paved the way for a home pregnancy test came out of NIH in the early 1970s. Scientists studying how hormones affect reproduction developed a way to identify and measure hCG as a means of better understanding its role in cancer and pregnancy. “They basically ended up inventing the pregnancy test,” says Leavitt. “They published a paper in 1972, but they didn’t get a patent. They could have been multimillionaires.”

In fact, the researchers did meet with lawyers, but they decided against commercializing their discovery. “They could not have guessed how big it would be, which was not necessarily a failure of imagination,” says Leavitt, who is now curator at the National Building Museum. “But they thought, Why would millions of women spend money to find out what they’re going to find out eventually?”

Their perspective made sense at a time when abortion was not legal, sophisticated prenatal diagnostic tests were not readily available, and fertility clinics were not the booming industry they are today. But in 1973, Roe v. Wade became law, and the pharmaceutical industry smelled potential. First to hit the market was e.p.t. (short for “early pregnancy test”), “but by like a minute,” says Leavitt. Other companies quickly followed suit.

The tests revolutionized early pregnancy, but historians are hard-pressed to track down an original. No one seems to have one. Because of its bulk, Insight Pharmaceuticals, e.p.t.’s parent company, suspects they’re as likely to end up locating one on a dusty shelf of a family pharmacy, the kind of place that collects old Sucrets tins and amber-tinted medicine bottles, as they are to find a kit buried in some woman’s bathroom cabinet.

To that end, Insight is putting out feelers to retailers, industry contacts and pharmacists and placing ads in publications such as Drugstore News and Pharmacy Times. “It would have to be someone interested in vintage medical devices,” says Jennifer Moyer, Insight’s vice president of marketing. “We’re turning over every leaf we can to find that person who says, Oh yeah, I have one of those. I’m convinced there has to be one somewhere.”